Light Guide Plate with Gradient Scattering Density
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Solution Overview
Problem
Large liquid crystal televisions face challenges in achieving a thin design with high light use efficiency, minimized luminance unevenness, and a convex luminance distribution, as existing backlight units either compromise on thickness, luminance, or increase manufacturing costs due to complex configurations.
Innovation Solution
A light guide plate with a three-layer structure, where the particle density of scattering particles increases from the light entrance planes to the center, allowing for a convex luminance distribution and high light use efficiency, while maintaining a thin design, achieved through a specific configuration of layers and particle density distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a direct illumination type backlight unit is used to achieve uniform light amount distribution, then luminance uniformity is improved, but the thickness of the backlight unit increases to about 30 mm
Solution Approach 1:
The light guide plate is divided into multiple regions with different scattering particle densities: a first region closer to the light source with lower density, and a second region farther from the light source with higher density. This segmentation allows different parts of the plate to perform different optical functions, achieving both thin profile and uniform luminance distribution.
Solution Approach 2:
Different regions of the light guide plate are given different local properties through varying scattering particle densities. The first region has lower scattering density to allow light penetration, while the second region has higher scattering density to diffuse light effectively, creating optimal luminance uniformity in each zone.
2Length of stationary object
If the thickness of the light guide plate is reduced to achieve a thin design, then backlight unit thickness is improved, but light use efficiency decreases
Solution Approach 1:
The scattering particle density is changed as a key parameter across different regions of the light guide plate. By increasing particle density in the second region farther from the light source, the plate maintains high light use efficiency even with reduced overall thickness, as the gradient distribution optimizes light extraction throughout the thin structure.
3Ease of manufacture
If scattering particles are uniformly distributed in the light guide plate, then manufacturing simplicity is maintained, but luminance unevenness increases
Solution Approach 1:
Rather than uniform distribution, the patent applies local quality by varying scattering particle density across different regions. The first region has lower density and the second region has higher density, which compensates for the natural light intensity gradient and produces uniform luminance output across the entire plate surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a thin, efficient backlight unit with improved luminance distribution, achieving a convex curve illuminance distribution and maintaining high light use efficiency, thus addressing the limitations of existing technologies.
Implementation Method 1
a light guide plate for diffusing light emitted by an illumination light source
Data Source
AI summary
A light guide plate comprises: a rectangular light exit plane and at least one light entrance plane in contact with the light exit plane, wherein the light guide plate comprises three or more structural layers disposed on each other in a direction normal to the light exit plane, each structural layer containing scattering particles dispersed therein, the structural layers having different particle densities of scattering particles.